In general, clean air, suitable temperature and suitable humidity are important factors that determine the quality of indoor environments. Due to recent urbanization and industrialization, air present in the indoor spaces of urban and industrial facilities or the closed spaces of cars may contain various harmful substances. As used herein, the term “harmful substances” refers to infectious microorganisms that spread through air, organic pollutants, atmospheric pollutants, harmful odor gases, and the like.
Such harmful substances may weaken human immunity, and in severe cases, cause various diseases, including chronic bronchitis, lung function damage, etc., and directly threaten life. Under such circumstances, in order to improve the quality of air in indoor spaces or closed spaces, various air cleaning methods have been introduced.
An example of conventional air cleaning methods includes a method of performing air cleaning by adsorbing some dusts and harmful substances contained in air by the use of a nonwoven fabric or activate carbon filter mounted in an air vent or ventilation opening located in a duct. However, this conventional technology is a method of removing harmful substances by adsorption and has shortcomings in that, because harmful substances are not decomposed, the filter is required to be periodically replaced due to adsorption, thus reducing the lifespan of the apparatus used.
Another example of conventional air cleaning methods includes an air cleaning method that uses an ionizer or the like. This air cleaning method is a method of cleaning air in, for example, cars or air conditioners, and comprises filtering harmful substances in externally introduced air that is passing through an evaporator core and a filter coated with an antimicrobial substance. However, the air cleaning method that uses the ionizer has a problem in that ozone harmful to the human body is generated.
Still another example of conventional air cleaning methods includes a method that comprises removing particles such as dust from air using a HEPA filter, and then treating air with ozone or a titanium dioxide in order to generate anions or deodorize air. In this method, there are problems in that when a high voltage is applied across an electrode in order to activate the deodorization and sterilization functions of the bulk-type titanium dioxide catalyst having a lattice structure, a high electric field is applied to a portion of the electrode to cause electric discharge, resulting in a decrease in the efficiency of the catalyst, or the use of the high voltage involves the risk of fire, limits the thickness of the catalyst and reduces the strength of the catalyst.
In order to solve the above-described problems, an air cleaning method that uses a UV lamp can be considered. However, the air cleaning method that uses a UV lamp has a limitation in that it can be applied only to a place that guarantees the durability of the UV lamp and can receive the size of the UV lamp. For example, if the air cleaning method that uses the UV lamp is applied to a car, the UV lamp can be easily broken by the vibration or impact of the car. For this reason, it is difficult to actually apply this method to cars.
In addition, an air cleaning method that uses a UV lamp and a photocatalyst has shortcomings in that the size of the UV lamp makes it difficult to miniaturize the air cleaning apparatus and in that a relatively large amount of power is consumed to activate the photocatalyst, because the UV lamp includes, in addition to a wavelength that is used for activation of the photocatalyst, a number of wavelengths that are not used for activation of the photocatalyst.